In his Lectures on Literature, these are Nabokov's opening and closing sentences in his (three-page) discussion of the portion of Jane Austen's Mansfield Park in which Fanny visits the Portsmouth relatives:
The novel, which shows signs of disintegrating, now lapses more and more into the easy epistolary form. This is a sure sign of a certain weariness on the part of the author when she takes recourse in such an easy form. [...] The Portsmouth interlude--three months in the life of Fanny--and the epistolary form of the novel is ended. We are back where we were, so to speak, but the Crawfords are now eliminated. Miss Austen would have had to write practically another volume of five hundred pages if she had wished to narrate those elopements in the same direct and detailed form as she had done in relating the games and flirtations at Mansfield Park before Fanny left for Portsmouth. The espistolary form has helped to prop up the structure of the novel at this point, but there is no doubt that too much has happened behind the scenes and that this letter-writing business is a shortcut of no very great artistic merit.So it is amusing when, in chapter four, our narrator engages in a bit of literary criticism of the epistolary form:
There are in my possession two more letters written on similar paper, but all the answers have been destroyed. If I still had them [...] it would be possible now to adopt an epistolic form of narration. A time-honoured form with great achievements in the past. [...] The reader soon ceases to pay attention whatever to the dates; and indeed what does it matter to him whether a given letter was written on the ninth of September or on September the sixteenth? Dates are required, however, to keep up the illusion.A few pages later in the same chapter, there is what may or may not be an allusion to Proust:
So it goes on and on, Ex writing to Why and Why to Ex, page after page. Sometimes an outsider, a Zed, intrudes and adds his own little contribution to the correspondence, but he does so with the sole aim of making clear to the reader (not looking at him the while except for the occasional squint) some event, which, for reasons of plausibility and the like, neither Ex nor Why could very well have explained.
But while I looked there started afresh that process of fusion, of building, that making up of a definite remembrance [...] I could not discover what the kernal was, around which all those things were formed, and where exactly the germ, the fount--suddenly I glanced at the decanter of dead water and it said "warm"--as in that game when you hide objects; and very possibly I should have finally found the trifle, which, unconsciously noticed by me, had at once set going the agent of memory...